To provide ammunition training for its troops, the U.S. Army uses a wide variety of training cartridges for different types of gun systems. These training cartridges are designed and developed to simulate ballistics of existing tactical cartridges. They are typically designed to provide audible and visible signatures to simulate a deployment and to acquire an impact point. Typical signatures of the deployment are flash or smoke, and bang. These signatures are commonly generated by a proper function of fuze.
Training rounds are typically made fragmentation free by removing explosives for the safety of soldiers. To meet this need, non-explosive fills are commonly used for simulating physical properties including weight, the center gravity location, and moments of inertia.
The training cartridges simulate tactical cartridges with the following added advantages. They are cheaper to produce as they lack the explosive charges, they are environmentally friendly, they are more reliable, and they are safer to use especially when training new recruits. For example, the 60 mm, M766 Short Range Practice Cartridge and the 81 mm, M880 short range practice cartridge use a method to release smoke signature through the holes located around an ogive section (forward body section). These training rounds are equipped with a point detonating fuse that functions by impact. These types of training rounds are realistic and effective mortar crews for gaining hands-on experiences and target practices.
However, the signature method of M766 SRPC and M880 SRPC could be improved further. As stable projectiles fall with the nose down, and the round can dig in to the ground fast and deep. Since the vent holes for smoke release are locating on ogive section, the holes can be blocked before provide full signatures.
It would therefore be desirable to enhance this signature method as applied to the 60 mm, M769 by delaying the hole blockage during impact.